NetworkReplyHttpImplPrivate::_q_startOperation was called more than once

In Qt 5.12.0, requesting a URL with QNetworkAccessManager::get() produces the following debug message:

QNetworkReplyHttpImplPrivate::_q_startOperation was called more than once QUrl("[requested URL]")

This message isn't produced when running the same code in Qt 5.11.2, or earlier versions of Qt.

To confirm this wasn't an issue with other parts of my code, I wrote the below minimal test.

#include <QApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QNetworkAccessManager* manager = new QNetworkAccessManager(nullptr);
    manager->get(QNetworkRequest(QUrl("http://www.google.com/")));
    return app.exec();
}

This produces the debug message:

QNetworkReplyHttpImplPrivate::_q_startOperation was called more than once QUrl("http://www.google.com/")

This message doesn't appear to impact the functionality of the program, and in my main program the requested URL is still retrieved as normal.  However, it does appear to indicate a problem with Qt 5.12.0 that may need addressing.